As cardinals from around the world gather in Rome to begin choosing a new Pope following the surprise resignation of Benedict XVI last month, LIFE.com has published a collection of unique images of the Catholic headquarters shot more than half a century ago.

Nat Farbman traveled to the Vatican for LIFE in 1950 and documented "The Search for the Bones of St. Peter," the quest of a group of excavators to locate the skeleton of St. Peter in the tombs and catacombs of the Vatican.

From LIFE.com:

Deep in the earth below the great basilica of St. Peter’s in Rome the clink of pickaxes and the scrape of shovels in the hands of workmen have been echoing dimly for 10 years. In the utmost secrecy, they have penetrated into a pagan cemetery buried for 16 centuries. Architects feared they might disturb the foundations on which rests the world’s largest church. But the workmen, with careful hands, pushed forward finally to the area where, according to a basic tenet of the Catholic Church, the bones of St. peter were buried about A.D. 66.

Only a select few of Farbman's images made it into the March 27, 1950 issue. However, many were published this week on the LIFE.com website.

Check out HuffPost's favorites in the slideshow below or visit LIFE.com for the full gallery.

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  • Foreman of work crew, photographed during the excavation beneath St. Peter's in Rome, 1950.

  • A workman cleans an inscription during the excavation beneath St. Peter's in Rome, 1950.

  • Workmen examining underneath the floor of Basilico.

  • Scene during the excavation beneath St. Peter's in Rome, 1950.

  • Workers gauge damage from water seepage during the excavation beneath St. Peter's in Rome, 1950.